crossbeams

Crossbeams are structural members that extend across a space to carry loads and stabilize a frame. They are usually horizontal but can be inclined as part of braces or formed as a lattice. Crossbeams transfer weight from floors, roofs, or decks to supporting posts, walls, or girders and often work in conjunction with joists, rafters, or beams.

In timber framing and traditional construction, crossbeams run perpendicular or at right angles to the main span and help distribute loads across the frame. They are typically connected with mortise-and-tenon joints, timber bolts, or metal connectors, and may be surfaced or chamfered for fit and finish. In modern buildings, crossbeams may be steel or reinforced concrete, forming part of floor systems or roof decks.

In bridges and larger structures, crossbeams—often called transverse girders or cross girders—span between longitudinal members to carry loads across a deck or roadway. They can be I‑beams, box girders, or solid slabs in concrete construction, designed to resist bending and shear.

In scaffolding and temporary structures, crossbeams or cross pieces form a lattice that supports platforms and distributes weight to uprights. Exposed crossbeams in interiors may serve decorative or acoustic purposes, as part of ceiling grids or timber ceilings.

Materials commonly used for crossbeams include wood, steel, and reinforced concrete. Key design considerations are load paths, spacing, joint quality, connection details, and resistance to deflection, rot, or corrosion.